Traditionally, powdered sweeteners for animal feed are composed of a statistical mixture of two powders with very different particle sizes, i.e. a sweetening powder with a relatively coarse particle size and mixed with a potentiator in the form of a much finer powder. The sweetener, i.e. the agent bringing the sweet flavor is usually saccharine or sodium or calcium saccharinate, or sometimes other natural or artificial intense sweeteners.
The potentiator has a double role. Firstly, as its name indicates, it has the effect of extending the perception of the sweet flavor which, in its absence, would be too short. A good potentiator, as those classically used, allows an increase of the sweet perception time by approximately 50 to 80%. The other effect of the potentiator, and not the least, is to hide the secondary or parasitic tastes of the sweetener, e.g. the bitter, metallic taste of saccharine or its sodium or calcium salts.
For practical reasons of the disclosure and for a better understanding of the problem set herein, we hereinafter refer more particularly to the feeding of piglets, although the invention applies to other young reared animals such as young bovines, sheep, goats, horses, deer, etc.
For piglets, the consumption must be optimal during the weaning time, in order to ease the transition from maternal milk to solid feed. This phase brings an increased vulnerability for the piglets' health and, to prevent disease risks, the feed is sometimes supplemented with repulsive-tasting medicinal products. This is intended to stimulate its appetite so that it eats the maximum feed, by serving rations containing sweeteners, the young animal being especially fond of the sweet flavor it was used to with its mother's milk. For instance, a weaned 28 day old piglet weighing 6.5 to 8 kg, eats 200 to 300 g per day of food, usually in granulated form. A piglet absorbs with each mouthful approximately 8 g, that is some fifty granules, which is very little. But, as from the age of 8 days, the piglet is already given granulated feed under the mother for it to get used to its future diet. It only eats 30 to 40 g per day, which represents only some ten granules per mouthful. With or without medical supplementation, its appetite is stimulated by proposing tasty food and this is why it has become usual to give granules with incorporated sweeteners. These granules, weighing about 0.15 g with a mean diameter of 0.3 cm and a length of 1.5 cm, are composed of a sweetener in an amount of approximately 1/4 by weight dispersed on a support, of approximately 3/4 by weight, which can be dextrose silica, ground cereals or combinations thereof. The proportion of saccharine to the potentiator is in the order of 100 to 1-2 and approximately 400 g/t (gram per metric ton) of this mixture is added to the final food.
In order to avoid any ambiguity, in the terminology used hereinafter the word "sweetener" shall be used to designate the sweetener/potentiator mix, object of the invention, as well as traditional corresponding products which will serve as comparison, whereas the expression "sweetening formulation" or "sweetening premix" shall be used when the sweetener proper is dispersed in a support. This sweetening formulation, which in a way is a seasoning like salt or pepper for human foods, will then be incorporated into the final feed given to the piglet.
Traditional sweeteners are statistical mixtures of one or more sweeteners and of one or more potentiators which have, as stated before, very different particle sizes. In spite of the care which can be brought to their realization, this can only result in mixtures with a great heterogeneity. They will therefore be named hereafter "coarse sweeteners".
This great inhomogeneity, conjugated with the absorption by the piglet of a very reduced number of granules per mouthful, leads to the effect felt by the young animal possibly being very different from one mouthful to another (and leading to variations of consumption): one mouthful can have a hardly-perceptible sweet taste, whereas the following mouthful can be too sweet or event bitter and metallic because of difficulties to hide the aftertaste of the saccharine, in spite of the potentiator, when it is too concentrated. Traditional sweetening formulations, based on coarse sweeteners, although widely used in rearing for lack of better, only give moderate satisfaction.
Generally, questions linked to the use of sweeteners in animal feed are curiously infrequent in the literature and we will quote for example the disclosure of DE-2 029 749 which has no relation to the object of the present invention, because it concerns a nutrient formed of a layer of sweetening substance and containing assimilable iron.